Conventional systems exist that perform gesture recognition, i.e. interpreting user motion as input to a system. For example, touch screen based systems collect user inputs using a touch screen that monitors changes in capacitance on the touch screen to identify the position of user input from a stylus or finger in contact with the touch screen. Changes in the capacitance are interpreted to determine the user's motion. By way of another example, some optical systems capture optical input on a pixel basis and identify motion by analyzing changes in the pixel data.